Binge Eaters’ Brains React Strongly to Food

When binge eaters complete treatment for an eating disorder and return to normal life, they often struggle with repeated relapses back into the disordered eating behavior. Training patients to control their responses to stimuli that induce binge eating is regularly included in treatment, helping patients recognize the triggers that precede their bingeing episodes. A recent study indicates that what is being triggered is a chemical in the brain of the binge eater, cueing pleasure receptors to get ready for a surge of calories. The research, conducted at the U.S. Department of Energy’s Brookhaven National Laboratory shows that when comparing ordinary obese participants with those who binge eat, there is a difference in how they respond to the sight or smell of favorite foods. The study’s lead author, Gene-Jack Wang, a physician at Brookhaven Lab and the Mount Sinai School of Medicine, explains that the exposure to food triggers a spike in dopamine, which is a chemical in the brain that controls reward and motivation. The findings of the study are published in the online journal Obesity, showing a connection between the dopamine spike and compulsive overeating. In previous studies, Wang’s team has shown that there are similar surges in dopamine exhibited in drug-addicted individuals when they are exposed to images of people taking drugs. The researchers expected to see results showing that binge-eating subjects would react more strongly to food stimuli when compared to non-binging obese subjects. The researchers hoped that they would see results that would point to neurobiological mechanisms that might be regulated to alter disordered eating behaviors. The study recruited ten obese people who had been diagnosed with binge eating disorder and eight people who were obese but not binge eaters. The subjects were exposed to their favorite foods after 16 hours of fasting, which were prepared to be enticing (such as heating foods that were meant to be eaten warm). The researchers waved the foods in front of their mouths and noses so that they could smell the foods and even swabbed tiny amounts onto the tongues of subjects. The subjects were also exposed to non-food-related pictures and inanimate objects such as toys or clothing, which were also offered to the subjects for smelling while lying in the scanner. The results showed that food stimulation significantly increased dopamine levels in the brains of the binge eaters but not in the non-binge eaters. Dopamine levels were not elevated under any other condition tested in either group. Because binge eating disorder is not limited to obese individuals, further research is necessary to determine the role of dopamine in not only obese binge eating individuals, but also in normal weight and underweight individuals who binge eat.